Portage Learning: A&P II: Cardiovascular System

circulatory system

(aka cardiovascular system) This system works as the transportation highway for the body. It consists of the heart, blood, and blood vessels. It transports substances such as oxygen, carbon dioxide, and nutrients in the body.

T or F: Every cell in the human body must be supplied with oxygen and nutrients and rid itself of waste

True, made possible by circulatory system

cardiovascular system

A closed circulatory system with a heart and branching network of arteries, capillaries, and veins.

- fluid contents are pumped from the heart and throughout the body and back to the heart

Cardio

heart

Vascular

vessels

what is the function of the cardiovascular system?

blood circulation and removal of carbon dioxide to oxygen

- prevents the loss of blood from ruptured vessels through clotting mechanisms

transportation of gases, nutrients and wastes

- fights invasion of foreign pathogens

heart

A hollow, muscular organ that pumps blood throughout the body.

Where is the heart located?

Pericardial cavity within the mediastinum

Three layers of the heart

pericardium, myocardium, endocardium

Pericardium

Double-layered membrane surrounding the heart.

- tough, thick sac

- protects the heart and anchors it to the diaphragm

- covered by endothelium

Endothelium

lubricating fluid between the layers allows the heart to slide around with very little friction

Myocardium

muscular, middle layer of the heart

- "bulk" of the heart

Endocardium

inner lining of the heart; continuous with the blood vessels

4 chambers of the heart

2 atria and 2 ventricles

Atria

2 upper chambers of the heart; smaller than the ventricles

Ventricles

the two lower chambers of the heart, and they pump blood out to the lungs and body.

septum

Divides the right and left chambers of the heart

fossa ovalis

a shallow depression in the interatrial septum that marks the spot where an opening, the foramen ovale, existed in the fetal heart.

- allows fetal blood to move directly from the left to right atrium, bypassing underdeveloped lungs

- closes during birth

Valves

Flaps of tissue that open and close to allow the flow of blood in one direction only. The heart's valves are located at the entrances and exits of its chambers.

why are valves important in the functioning of the heart?

- if we have backflow of blood something called regurgitation will occur; bad for the heart; will cause clogging and not moving forward in the direction it needs to go to function

Four one-way valves of heart

pulmonary, aortic, mitral, tricuspid

pulmonary valve

controls blood flow from the right ventricle into the pulmonary arteries, which carry blood to your lungs to pick up oxygen

aortic valve

controls the blood flow out of left ventricle into the aorta

why is the aortic valve stronger than the pulmonary valve?

increased blood pressure needed to send blood pumping to the entire body, left ventricle is stronger and thicker vessel because it is sending blood into our body

mitral valve

valve between the left atrium and the left ventricle; bicuspid valve

tricuspid valve

valve between the right atrium and the right ventricle

Blood flow through the heart

1. RA

2. Tricuspid valve

3. RV

4. Pulmonary semilunar valve

5. Pulmonary trunk

6. Pulmonary arteries

7. Lungs

8. Pulmonary veins

9. LA

10. Bicuspid valve

11. LV

12. Aortic semilunar valve

13. Aorta

14. Body

3 types of blood vessels

arteries, veins, capillaries

Arteries

carry blood away from the heart

- elastic, thick walled-vessels can expand and contract and accommodate the larger blood volume flowing the heart at each heartbeat

- contain palpable pulses

palpable pulses

able to be felt; feel the pulse inside the artery

Arterioles

small vessels that receive blood from the arteries

- constricted and dilated by the autonomic nervous system, controls blood pressure,

What happens when the arterioles contract?

blood flow is diverted away from their tissues

- increases blood pressure; through decreasing available volume

What happens when the arterioles dilate?

relaxation of the arterioles and volume increase

peripheral resistance

vessels responsible for varying blood pressure levels to blood flow depending on the external and internal conditions affecting the body

Veins

Blood vessels that carry blood back to the heart

- thinner - walled vessels that are under less pressure from the heart

Do veins have pulses?

No because by the time the blood gets from the arteries to the arterioles and into the vein there is a much more steady blood flow that is not detectable from a pulse

why do veins have internal valves?

Veins have internal valves that open toward the heart and close at the end of the heartbeat to prevent blood from flowing backward as the blood is returned back to the heart; only open to the heart; to prevent backflow from the blood

compliance of veins

stretch with little recoil; not as much elastic as arteries

- because of their compliance, veins have the largest amount of blood in the cardiovascular system

lumen

opening center of a vessel

arteries and veins have three layers

tunica externa, tunica media, tunica intima

tunica externa (adventitia)

most superficial layer of vessel; keep our vessels where they are are supposed to be going able to to continually supply blood to the muscles or region of the body

tunica media

middle layer of artery; made up of smooth muscle fibers and thick layer of elastic connective tissue

tunica intima (interna)

layer of vessel that contains a layer of subendothelial tissue and a layer of endothelium; lines the lumen

Capillaries

exchange materials with tissue

- start of very large arteries need to get small so they are one cell thick

why are capillaries so small?

To slow the blood and allow exchange of nutrients and oxygen

what causes the formation of narrowing capillaries?

branching of arterioles

capillary beds

sites of chemical exchange between the blood and interstitial fluid

Venules

small vessels that gather blood from the capillaries into the veins

Blood Supply to the heart

two artery systems that arise from the base of the aorta and supply of oxygen and nutrients to the heart tissues:

Left coronary artery and right coronary artery

left coronary artery

one of two arteries from the aorta that nourish the heart; (runs from left side of heart then divides into the circumflex and left anterior descending branches)

anterior interventricular branch and circumflex branch

arise off of the base of the aorta

anterior interventricular branch

supplies blood to both ventricles

circumflex branch

supplies left atrium and left ventricle

Right Coronary Artery (RCA)

run toward the right side of the heart and divides into the posterior interventricular artery and marginal artery

posterior interventricular artery and marginal artery

which supply the right atrium and right ventricle; arise off of the base of aorta

Blood supply to the body

1. Aorta

2. Aortic arch

3. Descending aorta

4. Thoracic aorta (above the diaphragm)

5. Abdominal aorta (below the diaphragm)

6. Many branches throughout to supply the blood tissues

Once blood leaves the heart it leaves and spreads throughout the body.

aortic arch

turns posteriorly and becomes descending aorta

thoracic aorta

in the thoracic; above the diaphragm

The descending aorta becomes?

abdominal aorta

Venus blood flow

inferior vena cava and superior vena cava

inferior vena cava

returns deoxygenated blood from the body

superior vena cava

returns the blood to the heart from the upper part of the body

brachiocephalic trunk

The first large artery arising from the aortic arch. It carries oxygenated blood to the neck, head, and right forelimb.

Left Common Carotid

second branch of the aortic arch

right common carotid

branch of brachiocephalic trunk

left subclavian artery

third branch of the aortic arch

right subclavin artery

branches off of the brachiocephalic trunk

Some major arteries and veins have matching names if running together in a parallel location

- right and left subclavian arteries and right and left subclavian veins parallel each other on the left and right sides of the body dumping their blood into the superior or inferior vena cava to the right atrium

Blood supply to the brain

Circle of Willis

Circle of Willis (cerebral arterial circle)

1. vertebral arteries rise superiorly along both sides of the spinal cord joining to form the basilar artery "upside down V"

2. Basilar artery branches into left and right posterior cerebral arteries

3. Posterior communicating arteries connect left and right carotid arteries

4. Internal carotid arteries: arise from the common common carotid arteries in the neck

5. Internal carotid arteries: terminate in the left and right middle cerebral arteries

6. Anterior cerebral arteries are connected by the anterior communicating artery, completing the circle of circulation

What is the unique feature of the circle of Willis?

provides alternate circulation in case in case one artery gets blocked

Why is this feature of the circle of willis important?

neurons must be continuously supplied with oxygen or they will die off within minutes

blood

Connective tissue made of plasma, erythrocytes, leukocytes, and platelets.

Two main portions of blood

plasma and formed elements

formed elements

red blood cells, white blood cells, platelets

serum

plasma without clotting factors

How does Serum not have clotting factors?

made possible by letting blood sit in a tube until it clots and then centrifuging the sample to separate the solid and liquid portions in blood

- used in laboratory tests

Plasma

liquid portion; 90% of water

What are the functions of plasma in the blood?

- buffers pH, keeps it at 7.4 pH

- assists in transporting large organic molecules in blood and aids in clotting

- nutrients that pass from the digestive system into the body are transported by the blood plasma

- plasma in the blood that enters the kidneys are waste products that get transported to the urinary system

- maintains homeostasis by keeping heat

- transports electrolytes, components of the immune system and hormones

- osmotic pressure

osmotic pressure

net pressure in the blood that moves the tissues into the circulatory system

What drives osmotic pressure?

protein in the plasma that remain in the capillaries; water has an automatic tendency to flow towards the proteins

Hydrostatic pressure of blood

pushes fluid into the tissues by the pressure of blood pumping from the heart

Why are hydrostatic pressure and osmotic pressure important for the body?

homeostasis; so we can have an ongoing balance of blood pumping between osmotic pressure and hydrostatic pressure

- fluids flow into the tissue and then return to the circulatory system

red blood cells (erythrocytes)

small, biconcave, disk-shaped cells without nuclei

What are red blood cells function?

carry oxygen through hemoglobin

What gives red blood cells their color?

two cave surfaces that gives it its dark appearance

Are red blood cells the most abundant cell in the Blood. T or F?

True

How many red blood cells are in the body?

4-6 million

How much hemoglobin do red blood cells have?

250 million

Hemoglobin

An iron-containing protein in red blood cells that reversibly binds oxygen.

How are red blood cells manufactured?

red bone marrow of the skulls, ribs and vertebrae and the end of the long bones

anucleate

without a nucleus; red blood cells are anucleate

Erythrocytes Maturation Process

1. must lose their nucleus and synthesize hemoglobin before they are released into the blood - more room to carry oxygen

2. live for about 120 days; destroyed by liver and spleen

3. when destroyed hemoglobin is released so that iron can be reused and by red bone marrow

heme

iron-based, pigment part of hemoglobin; excreted by liver as bile pigments

white blood cells

Blood cells that perform the function of destroying disease-causing microorganisms

Leukocytes

white blood cells, fight infection

How are white blood cells different from red blood cells?

- larger

- large nucleus

- lack hemoglobin

inflammatory response

nonspecific defense against infection, characterized by redness, heat, swelling, and pain

Why when there is a inflammatory response does the body respond with swelling and redness?

increase in blood flow to the injured site which helps deliver the immune defense cells

How do white blood cells destroy pathogens?

by squeezing through the capillary walls and enter the tissue fluid, where they destroy any foreign material